The present invention relates to devices for collecting aquatic specimens and more particularly to a new and improved lightweight, multi-positional frame to which the specimen collection nets can be attached.
In the past there have been various devices used for underwater sampling of plankton specimens. By way of example is U.S. Pat. No. 3,461,591, wherein an underwater sampling apparatus is described. The underwater sampling apparatus includes a pair of cylindrical hoops joined in side by side spaced relationships by a bar. It is towed through the water by a tow line connected to the bar which connects the pair of hoops. Initially, each hoop has a cover over its front to prevent the passage of water through the hoop and into the nets which are connected to the hoops also. When sampling begins, the covers or flaps are released from the front of the hoops and allow passage of water into the collection nets. When the desired sampling is completed, each sampling net is released from the respective cylinder and as the net pulls away from the cylinders is closed by the choker cords. However, this apparatus has proved cumbersome and dangerous to use in heavy weather due to its heavy weight, and has not been well accepted by marine researchers.
Also, a need has arisen in the aquatic research field for an apparatus which will enable simultaneous aquatic sampling over a range of depths. Therefore, an apparatus which lends itself to sampling in series over a range of depths is required.
The present invention overcomes the deficiencies in the prior art devices, by providing a lightweight, multi-positional frame which is easy and safe to use even in heavy weather conditions. The structural design of the invention makes it readily connectable to any of the release mechanisms presently used for connecting the sampling devices to the tow cable of the ship, and provide for flexibility of opening either mechanically, hydrostatically, or electronically. The present invention also eliminates the need for the use of flaps to initially prevent the flow of water specimens into the collection nets which affect the accuracy of the flow meter information. Such flaps preclude the mounting of flow meters in the mouths of the nets rendering accurate quantative measurements impossible. The present invention, with frames closing upon themselves, has no such restriction. Flow meters can be mounted in the mouths of the nets permitting actual measurement of flow volume through the nets.